The aim of this project is to map and identify QTLs relevant to the development of renal failure in a cross between HIV-1 transgenic (Tg26) and M. castaneus (CAST/Ei) strains. To achieve this goal, we have performed genome-wide analysis of linkage in 192 backcross animals and found two loci with significant evidence of linkage on chromosome 8 (Iod 5.4) and chromosome 3 (Iod 3.5). Tow other loci on chromosomes 13 and 16 showed suggestive evidence of linkage (Iods 2.0). The 40 cM linkage interval on chromosome 8 comprises the transgene integration site, suggesting that the transgene or flanking loci influence the expression of the trait. The aims of this project are: 1. Develop congenic mouse strains by marker assisted breeding in order to "capture" the renal disease loci detected by linkage on chromosomes 8 and 3 and loci with suggestive Iod scores. After phenotypic characterization, we will proceed with meiotic mapping of the QTL in congenic strains, followed by identification of the gene(s) responsible for the development of renal failure by candidate gene analysis and positional cloning. 2. Characterization of the linked interval chromosome 8 interval that comprises the transgene integration site. Our preliminary data indicate that the transgene has integrated in the genomic locus of a novel gene, resulting in a complex rearrangement including gene duplication. We will characterize the transgene integration site and ensuing genomic re-arrangement by comparing RNA and protein expression of the novel gene and determine its tissue and cellular localization in wild-type, heterozygous and homozygous transgenic mice. These studies will also be conducted in chromosome 8 congenic mice trapping loci flanking the transgene.